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MELSEC-QnA
15 FUNCTIONS (FUNCTION VERSION B OR LATER)
15.5.3 Link special relays/registers (SB, SW) relating to the standby master function
The link special relays and link special registers relating to the standby master function
are explained.
They are stored in the buffer memory.
(1) Link special relays (SB)
The link special relays (SB) relating to the standby master function are as follows.
The figures in parentheses in the number column indicate buffer memory
address and bit location.
Example: When buffer memory address is 5E0
H and bit location is 0: (5E0H, b0)
Table 15.4 List of link special relays relating to the standby master function
Availability
(
: available, : not available)
Number Name Description
Master station
Standby master
station
SB0001
(5E0
H, b1)
Master station switch data
link start
Switches the output information from the standby master
station to the master station to start the data link.
OFF : No request
ON : Request
SB0042
(5E4
H, b2)
Master station switch data
link start acceptance
status
Indicates the acceptance status specified for switching data
link start from the standby master station to the master station.
OFF : Not accepted
ON : Accepted
SB0043
(5E4
H, b3)
Master station switch data
link start complete status
Indicates the acceptance complete status specified for
switching data link start from the standby master station to the
master station.
OFF : Not completed
ON : Completed
SB0070
(5E7
H, b0)
Master station data link
status
Indicates the data link status.
OFF : Data link by the master station
ON : Data link by the standby master station
SB0071
(5E7
H, b1)
Standby master station
information
Indicates whether there is standby master station or not.
OFF : No
ON : Yes
(2) Link special registers (SW)
The link special registers (SW) relating to the standby master function are as
follows.
The figures in parentheses in the number column indicate buffer memory
address.
Table 15.5 List of link special registers relating to the standby master function
Availability
(
: available, : not available)
Number Name Description
Master station
Standby master
station
SW0043
(643
H)
Master station switch data
link start result
Stores the results of execution of the master station switch
data link start instruction by SB0001.
0 : Normal
Other than 0 : Stores error code (Refer to Section 13.3)
SW0073
(673
H)
Standby master station
number
Stores the standby master station number.
1 to 63 (stations)